In recent years, electrically powered vehicles that travel by a driving force from a motor, such as hybrid vehicles, fuel cell vehicles, and electric vehicles, have received attention as one solution for environmental issues. Such an electrically powered vehicle is provided with a secondary cell such as a battery. As a secondary cell included in a power supply for driving a vehicle, nickel-hydrogen batteries, lead storage batteries, or the like are conventionally used.
A secondary cell used for driving a vehicle is often installed inside a vehicle interior, in order to cool the secondary cell by air-conditioned air in the vehicle interior. In particular, in order to efficiently use the capacity of an air conditioner for a vehicle interior, air in the vehicle interior is fed to the secondary cell to cool the secondary cell, and then the warmed air is returned inside the vehicle interior where the warmed air is cooled by the air conditioner for the vehicle interior. In this way, higher efficiency of the air conditioner can be achieved as compared with the case where air is exhausted out of the vehicle after cooling the secondary cell. Further, because no duct connecting the secondary cell to the outside is required, noise inside the vehicle interior can be reduced by avoiding noise which would intrude through the duct.
Further, use of a lithium ion battery as a secondary cell for driving a vehicle is becoming more common, because the lithium ion battery has higher energy density and downsizing capability than a nickel-hydrogen battery or a lead storage battery. However, the lithium ion batteries have a risk that smoke is generated due to a short circuit or the like in the lithium ion battery when a battery pack receives an impact due to a collision of the vehicle or the like. In such a case, if a secondary cell is installed inside the vehicle interior as described above, the generated smoke enters the vehicle interior and therefore, it becomes necessary to exhaust the smoke out of the vehicle interior.
Therefore, there is proposed a method for exhausting smoke out of a vehicle interior in which even if smoke is generated from an internal lithium ion battery upon a battery pack receiving an impact, the generated smoke can be exhausted out of the vehicle by establishing communication, in advance, between the vehicle interior and the outside of the vehicle when a collision or the like of a vehicle is predicted (for example, refer to JP 2007-99075 A (Patent Document 1)).